Caster



G.'P. BULL CASTER Filed Sept. 3, 1925 June 15 1926.

INVENTOR A'r-ronnzv FIGURE 2 Patented June 15, 1926.

UNITED STATES PATENT OFFICE.

GEORGE r. BULL, or SAN JOSE, CALIFORNIA.

GASTEB- Application filed September as applied to a trailer vehicle.

Figure 2 is a plan view of a caster em bodylng my invention and illustrating its mode of operation.

Figure 3 is a section on line 33 of Figure 2. I

Referring more particularly to the drawing, I show at 1 a plate mountable upon the under side of a vehicle or movable body in any suitable manner and having one plate as 2 of a ball bearing mounted thereon as an integral part thereof, the other plate being shown at 3 and the balls at 4.

Plate 2 has a concentrically arranged annular 'recess5 formed therein and carries a central depending pivot 6, while plate 3 is provided with an annular boss 7 and socket 8 to engage the recess and pivot 6 of plate 2.

Eccentrically mounted on the bottom of plate 3 is the upper plate 9 of a ball bearing somewhat smaller than the .bearing above' described and as clearl shown in Figure 3. An axially arranged pivot 10 depends from plate 9 and passes through the top of a post 11 which carries the bottom plate 12 of the bearing, the balls being shown at 13.

The post 11 has an offset lower end portion 14 through which the axle 15 of wheel' 16 asses, and when the caster is used on a trai er vehicle as 17 it may be fitted with springs 18.

.. At 19, is shown a bracket bolted to the under side of the late 1 and extending downwardly and un er plate 2 as shown at 20 in Figure 3, this portion'20 having its inner ed e formedas shown at 21-21 to engage p ate 12 on post 11 and form a stop for the plate 2; Thisfpart 20 is so formed and pro ortioned that when the vehicle 17 is move forwardly or backwardly the en- 3,;1925. Serial No. 54,256.

gagement of plate 12 therewith at all times holds the pivot 10 offset a distance relative to a vertical plane passing through-the pivot 6 in the direction of the line of movement of the vehicle.

With the vehicle moving in the direction indicated by arrow 22 the parts normally assume the positions indicated by the several reference numerals as heretofore applied. When, however, the direction of movement of the vehicle is reversed and caused to travel in the direction indicated by arrow 23 the frictional contact of wheel 16 with the ound causes the post 11 to turn on bearings 9, 10, 12 while the plate 3 carrying bearing 9, 10, 12 also turns on the bearing 2, 3, 4, so'that when the reversing movement is half completed the points 15, 10, 6 are in the relative positions 15, 10, 6, and when the reversing movement-is completed these polnts are'in the positions 15", 10", 6

In performing this maneuver the wheel.

16 merely pivots on a substantially fixed vertical axis 24, while the pivot 10 passes by on the outer 'side thereof and the pivot 6 passes by on the inner side thereof.

This movement is accomplished with a minimum amount of friction and eflectually eliminates excessive side thrust of the wheels 16 when the direction of movement of the vehicle is changed or reversed.

' The device is also effective in turning because in makin a turn the pivot wheel oper-.

ates freely so t at side thrust is eliminated, and the outer wheel is held in its'normal position by stop 20.

It is to be understood, of course, that while I'have herein shown and described one specific embodiment of the invention,

' changes in form, construction, and method of operation ma be made within the scope -of the appende claimsm cla1m:

1. A device of the character described comprising a ball bearing mountable upon the under side of a horizontally movable body, a second ball bearing of less diameter than the first eccentrically mounted upon the lower side thereof and carrying a w eel supporting element having anofi'set lower end, a wheel ournaled on said ofiset end,

and means for limiting the rotation of said first bearing.

2. A device of the character indicated comprising a ball bearing mountable upon and a stop positioned to engage said second the under side of a horizontally movable bearing whereby to maintain its axis of robody, a second ball bearing of lessdiameter tation offset with relation to the path of than the first eccentrically mounted u on travel of the axis of rotation of said first l the lower side thereof and carrying a W eel bearing.

susporting element having an ofl'set lower en a wheel journaled on said ofiset end, GEORGE P. BULL. 

